Seth Rogen might be a fun buddy to have if you’re staring at Schwannoma neurofibrosarcoma. That’s the form of cancer Will Reiser found himself looking at on an x-ray, clinging to his spine like some opportunistic parasite out of a David Cronenberg film.

Reiser was diagnosed in 2005 while he and Rogen were working together on Sacha Baron Cohen’s Da Ali G Show (he’s cancer-free now). 50/50 is the result, a fictionalized account of how Reiser (called Adam Lerner in the movie, and played by Joseph Gordon-Levitt) dealt with the crisis by basically not changing much. As the movie (written by Reiser) tells it, he and Rogen (playing a version of himself named Kyle) hung out a lot, getting high and laid; they led the sort of pleasantly grubby lives you’d expect of guys in their mid-twenties. In short, they disregarded the realities of cancer and mortality for as long as they possibly could.

50/50 is a quiet refutation both of cancer itself and of the usual movies about illness. It has a low-key integrity. It tries very hard not to be the sort of cancer movie that Reiser and Rogen would watch on DVD and make brutal fun of from the couch. It avoids many narrative clichés, though Reiser can’t help it that the scene in which Adam receives his diagnosis, and momentarily blanks out in shock while the doctor rattles on, is probably common enough among patients to have been depicted in illness stories quite a few times before. For the most part, there’s no manufactured drama here. Adam is sick, and yet his biggest problem is how everyone around him reacts. His self-absorbed artist girlfriend (Bryce Dallas Howard) says she won’t bail on him, but eventually does. She’s supposed to be the villain of the piece, but the relationship had been going south anyway; she just stuck around for a while because she didn’t want to be the bitch in the movie who walks out on the dude with cancer.

That may be the key to the film, really. 50/50 is full of people who have seen this movie before and know how they’re supposed to respond — supportively, selflessly. Since 50/50 is straining not to be that movie, almost everyone in it is baffled by reality — even Adam’s therapist (Anna Kendrick), who’s quite new at therapy, and quickly discovers that the various easy fallbacks (meditation music, etc.) won’t work so well on him. I wished for a spikier, more vibrant lead character, though. Joseph Gordon-Levitt plays Adam with uncommon delicacy and wit, but Reiser, as the semi-autobiographical screenwriter, may err on the side of modesty. Or maybe he really is this mild and untemperamental. Reiser gives Rogen, the scruffy baby Falstaff, the best lines and biggest laughs; it may be a thank-you gift from Reiser to the friend who made him laugh through pain.

The movie is being praised, and rightly so, for what it isn’t. But what about what it is? The absence of banality, sadly, does not equal originality. 50/50 is noble in its own way but not especially affecting. In its homey style and jokiness it’s as comfortable as an old shoe, and I don’t know that a movie about cancer should be comfortable.

There are a few scenes with great old hands Philip Baker Hall and Matt Frewer as cancer patients who take chemo along with Adam, and they’re in a different movie I wanted to see more of. These men are beyond bromides and even jokes; they just want to get high off weed-stuffed macaroons while waiting for the inevitable. They have a bitter gaiety in the face of death; on their last legs, they’re more vital than anyone else in the movie.